1. Technical Field
The present invention relates to warning lights typically for use in emergency vehicles. More particularly, the present invention relates to an apparatus for controlling the operating lights on a vehicle (such as headlights, parking lights, front and rear blinkers, tail lights and reverse lights) so that the operating lights may used for special purposes associated with emergency vehicles, particularly police vehicles.
2. Background of Invention
It is common for emergency vehicles, particularly police cars, not only to signal an emergency situation with rotary lights on the roof of the vehicle (light bars), but also to have the operating lights of the vehicle flash in a conspicuous manner. This flashing of the operating lights may be particularly important when dealing with partially marked police cars (cars without light bars but having decaling and flashing lights on the dash boards) and unmarked police cars.
Present devices for controlling the operating lights of a vehicle generally use mechanical relays or other conventional "hard-wired" circuitry. An example of this can be seen in U.S. Pat. No. 5,434,553 to Rhodes. There exist many inherent disadvantages when creating a given light flashing pattern or lighting function by use of hard-wired circuitry. First, there is the unalterable nature of the lighting function created by the circuitry. If it is found that the lighting function is not desirable or that it has specific disadvantages or limitations, the problem or disadvantage can only practically be corrected by replacing the entirety of the light control circuitry. Related to this disadvantage, the unalterable nature of hard-wired circuitry makes customization of the lighting system to a particular user impractical if not impossible. This may be very important when particular police departments desire, or internal policies require or forbid the use of certain light control characteristics.
Furthermore, hard-wired circuitry limits the complexity or number of lighting functions that may be perform because as the lighting functions become more complex or numerous, the sheer size of the circuitry becomes more impractical. This is particularly true where it is desired to place the main body of the circuitry in the interior of the vehicle (e.g. under the driver's seat) in order to take advantage of the more controlled environmental conditions such as temperature and humidity. Locating the light control device under the driver's seat also offers the advantage of a more protected location and will generally require less wiring to inter-connect the light switches and operating lights with the light control system. Therefore the size limitation when using hard-wired circuitry renders it less feasible when producing certain particularly desirable, but complex lighting functions. For example, the flashing of individual operating lights at frequencies different from the other operating lights rapidly increases the size of the system when using hard-wired circuitry. This is because a separate timing apparatus must be provided for each set of lamps to be flashed at a separate frequency as opposed to using a single timing element to control all frequencies. Additionally, when controlling lights in a special operating mode, it is often desirable to momentarily return several operating lights (but not all) back to their normal operating mode. For example, when the brakes are applied while the vehicle is in hyper-flash mode, the lights in the rear will operate in the normal mode while the lights in the front continue in hyper-flash mode. The amount hard-wired circuitry required to perform this function may render it impractical due to space limitations.
Still another disadvantage of hard-wired circuitry is the inherent limitation on how high of a frequency at which the operating light may be flashed before the intensity of the light is decreased. This phenomena is caused by the requirement that generally the lamp must receive power for a sufficient period of time in order for the filament to reach its full intensity. When the lamp is flashing, hard-wired circuitry will typically supply and discontinue power to the lamp (i.e. turn the lamp "on" and "off") at equal intervals. While the light is flashing at a 1 or 2 Hz frequency, power is being supplied to the bulb during the "on" cycle for a sufficient period for the filament to become fully energized. However, as the frequency reaches 4 and 5 Hz, the "on" interval is not sufficient to fully energize the filament and the lamp cannot reach its full intensity. Therefore a system that could flash the lights at a higher frequency and still maintain full light intensity would be a significant improvement in the art. Such a system would allow more conspicuous light flashing patterns and a larger selection of different flashing patterns.